Field of the Invention
The present invention relates to a vacuum processing apparatus which performs etching through plasma irradiation and optical heating.
Description of Related Art
Due to demands on a semiconductor device for achieving lower power consumption and increased storage capacity, further miniaturization and three-dimension of a device structure have been in progress. In manufacturing a device with a three-dimensional structure, the structure is sterically complicated, and thus in addition to “vertical etching” which is performed in a direction vertical to a conventional wafer surface, “isotropic etching” which can also be performed in a horizontal direction have been frequently used. Conventionally, the horizontal etching has been performed through the isotropic etching” by way of wet processing using chemical solution, but due the progressed miniaturization, a problem of pattern collapse caused by surface tension of the chemical solution has become obvious. Thus, in the isotropic etching, there have arisen needs for replacement of the conventional wet processing using the chemical solution with dry processing not using the chemical solution.
Known as a method of performing isotropic etching through dry processing with high accuracy (dry removal) is an etching method of an absorbing and desorbing type (for example, Japanese Patent Application Laid-open No. 2015-185594). With this method, radical generated by plasma is first absorbed to a surface of an etched layer of a processed body, and a reaction layer is formed through chemical reaction (absorption process). Next, heat energy is given to desorb and remove this reaction layer (desorption process). This absorption process and this desorption process are repeated alternately to perform the etching. With this method, in the absorption process, upon reach of the reaction layer, which has been formed on the surface, at a given thickness, the reaction layer prevents the radical from arriving at an interface between the etched layer and the reaction layer, thus rapidly decelerating growth of the reaction layer. Thus, at an inner part of a complicated pattern form, even with a variation in an amount of radical incidence, adequately setting sufficient absorption time permits formation of an altered layer with a uniform thickness, advantageously making it possible to make the amount of etching uniform without depending on the pattern form. Moreover, the amount of etching per cycle can be controlled at a level of several nanometers or below, thus advantageously permitting adjustment of an amount of processing with a dimensional accuracy of several nanometers.
[Patent Literature 1] Japanese Patent Application Laid-open No. 2015-185594